This type of aid has all the components in the device, which rests at the top of the ear, and there is an earmold in the ear with a hollow tube that runs from the mold to the device.
This type of aid has the speaker separate from the device. The device rests at the top of the ear with the speaker resting in the ear and is connected to the device with a thin electrical wire.
This type of aid has all the components in the device with the device in the ear. It is appropriate for mild to moderate hearing loss and is more visible than the other types of aids.